Today, the increasing popularity of mobile phones has led to the requirement that mobile phones must be able to operate in different settings, such as in humid environment and the like. A user that takes part in an outdoor activity wants to be able to bring the portable device with him and that no harm comes to the mobile phone due to dust, sand, moisture or the like.
To this end, a cover comprises resilient, softer parts that may be deformed enabling the user to press underlying buttons and the like. It also comprises substantially non-resilient, harder parts to impart stability to the cover. Transparent parts may be provided to make a display and buttons visible. There may also be parts letting sound pass, letting in sounds to a microphone and letting out sounds from speaker elements. The cover is customized to fit snugly a particular model of the portable device.
Suitably, the resilient parts are made from silicone or thermoplastic elastomer TPE or thermoplastic urethane elastomer TPU or combinations thereof. The substantially non-resilient parts may be made from hard plastic. The transparent parts may be made from high gloss plastic, and some parts may be made from plastic or glass with optical quality for location in front of camera lenses. Instead of transparent parts, the cover may be printed to indicate texts and symbols of underlying buttons. Sound permeable membranes may be made from air/gas permeable materials that are non-permeable to water and liquids, such as materials from Gore-Tex™. All such materials are known as such.
There is also a requirement that it should be easy to move the device from the cover and insert it again, when desired. Some people use the cover when working in hazardous environments, while other people spend their leisure time where the portable device may be exposed to water, dust and sand etc. Typically, a user wants to remove the device from the cover when the situation permits.
In the document U.S. Pat. No. 6,980,777 B2 a cover for a mobile phone is disclosed. The interior of the cover comprises surface features. However, these features are provided to retain the mobile phone within the cavity, i.e. to increase the friction between the mobile phone and the cover.